Generating a Makefile from Xcode
Almost all open source software projects I have encountered rely on GNU Make as a build tool. Make is a tool available on many platforms (most notably Linux and UNIX) that manages the compilation and installation of software programs. A Makefile defines the location of source files and steps required to compile and link targets to create the executable program file.
Importing existing Make-based software projects into Apple’s Xcode IDE is relatively easy; source files can be dragged and dropped into a Project, and Xcode will link and compile them automatically.
Unfortunately, porting Xcode Projects to other platforms is not so simple. While Xcode can integrate a Makefile as an External Build Target, it cannot export or create one. This functionality is granted with the use of a third party tool called PBTOMAKE. Note that Xcode was originally called Project Builder.
PBTOMAKE is a command line utility which creates a simple Makefile from an Xcode Project file. Integrating PBTOMAKE into an Xcode Project allows us to create a Makefile on the fly as part of the build process. Here’s how:
- Download and install PBTOMAKE, so that the ‘pbtomake’ command is available to the current user.
- In Xcode, ensure all Project file reference paths are specified Relative to the Project.
- Right click on the relevant build Target, and add a New Run Script Build Phase. Enter the following command:
pbtomake -i $PROJECT_NAME.xcodeproj -o path/to/Makefile
- Build your Project.
PBTOMAKE’s default compiler is GCC. Use the
-cc option to change compiler, and
-bin_dir to specify an alternate output directory.
An example cross-platform command-line application written in C++ which links against OpenSSL‘s libraries would use the following Run Script Build Phase to generate a Makefile from within Xcode:
pbtomake -i $PROJECT_NAME.xcodeproj -o path/to/Makefile -link_opt "-lssl -lcrypto" -no_framework -cc g++ -bin_dir path/to/bin
This method allows us to create and maintain C and C++ projects in Xcode, while providing excellent cross-platform portability via GNU Make.